[mapserver-users] Google Mercator and +nadgrids=@null

[Frank Warmerdam]

Jukka,

I believe the definition on spatialreference.org is out of date.  Recently
3785 generation was corrected for PROJ.4.

Best regards,

On Thu, Mar 18, 2010 at 5:27 AM, Rahkonen Jukka
<Jukka.Rahkonen at mmmtike.fi> wrote:
> Hi,
>
> I have in my epsg file the following line for Google Mercator
> projection:
>
> <900913> +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0
> +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs
>
> I have copied the definitions from somewhere, I do not remember where.
> Now I noticed that http://spatialreference.org/ref/epsg/3785/proj4/
> gives this proj4 string:
>
> +proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137
> +towgs84=0,0,0,0,0,0,0 +units=m +no_defs
>
> There seems to be one difference: my line has +nadgrids=@null while the
> Spatialreference one has +towgs84=0,0,0,0,0,0,0 instead. Do they mean
> just the same thing?
>
> -Jukka Rahkonen-
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>



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